Dense aggregations of the mudsnail, Ilyanassa obsoleta, typically overwinter subtid- 

 ally during New England winters. As water temperature increases in the spring, the 

 snails begin mass migrations back onto tidal flats where they begin reproducing and 

 feeding. Snails are approximately 2 cm in length. Photo by R.E. DeGoursey, Univer- 

 sity of Connecticut. 



algal mats and microalgae, decreased 

 sediment stability, and contributed to 

 increased erosion of the sediment-water 

 interface. Another species of naticid 

 snail, Lunatia heros , is occasionally 

 found on tidal flats in northern New Eng- 

 land although it is more abundant in sub- 

 tidal, sandy substrates. The whelk, 

 Busycon canal iculatum , also forages inter- 

 tidal ly in southern New England but is a 

 rare inhabitat of tidal flats. 



The mobile bay scallop ( Aequipecten 

 irradians ) is sometimes seen on tidal 

 flats. Settling juveniles prefer to attach 

 themselves by threads to eel grass ( Zostera 

 marina ) or other subtidal macroalgae. As 

 scallops grow, they drop to the sediment 

 surface in the vicinity of eel grass beds 

 and may move onto tidal flats at high 

 tide. 



Several species of epifaunal arthro- 

 pods are common to New England tidal 

 flats. Unlike the gastropods, this group 

 migrates on and off the flats with the 

 tidal cycle. The most common species 

 throughout New England is the green crab, 

 Carcinus maenas . Like all large crabs, 

 this species feeds by crushing its prey. 

 Feeding rates and preferred prey are re- 

 lated to crab size (Elner and Hughes 1978; 

 Elner 1980) with a tendency to specialize 

 on bivalves (e.g., ^1ya arenaria , Mytilus 

 edulis ). Ropes (1968) noted that these 

 crabs ingest annelids, detritus, and 

 Spartina blades as well. Other large crab 

 species are also present but are less 

 abundant than the green crab. The blue 

 crab, Callinectes sapidus . so very abun- 

 dant in the middle and southern portions 

 of the eastern seaboard, is less so in 

 New England, found only south of Cape Cod. 



23 



